94 SPECIAL BACTERIOLOGY 



On Agar it forms a white, moist, irregularly outlined covering. 

 On Potatoes, a shiny, thick, irregular patch is formed. 



Pathogenesis. In white mice and guinea-pigs an abscess some- 

 times forms instead of general septicaemia. Grey mice, dogs, and 

 rabbits are not susceptible. Macroscopically, no alteration can be 

 observed in the organs of dead animals, but microscopical examina- 

 tion will reveal the presence of the organism. In sections the 

 organisms will always be found within the capillaries. (See Photo- 

 micrograph, Fig. 30.) 



MICROCOCCUS GONORRHCEA. 



(Goxococcus NEISSER). 



This organism was discovered by Neisser in 1879 in gonorrhoeal 

 pus, and described by him as a ' gonococcus.' It was cultivated by 

 Bumm in 1885, and its infective influence proved by inoculation into 

 men. It is constantly present in virulent gonorrhoeal discharges, 

 generally in the interior of the pus cells, or attached to the surface of 

 the epithelial cells. 



Microscopical Appearances. Cocci usually jointed in pairs. 

 They are shaped like a pair of kidneys placed with the hilum in 

 apposition, or like a coffee bean, and are separated by a distinct inter- 

 space. The length of the gonococci is 0-8 /* to 1'6 p, diameter 0'6 to 

 0-8 IJL. 



Staining Reactions. It stains quickly with methyl violet, gentian 

 violet fuchsin, not so quickly with methylene blue, which is, however, 

 the best stain for demonstrating its presence in pus. (For special 

 staining methods see Technique, 16, 17.) The results with the Gram 

 method are negative, which enables it to be distinguished from other 

 common pus cocci. Though, according to Bumm, other diplococci 

 sometimes occur in gonorrhoeal pus that do not stain by the Gram 

 method, the most trustworthy diagnostic character is that the gonococci 

 are found within the pus cells sometimes in one or two pairs only, 

 frequently in considerable numbers, and sometimes almost filling the 

 cells. (See Photomicrograph, Plate IV., Fig. 24.) 



Biological Characters. The gonococcus grows only at 37 C. 



Plate Culture Method. The gonorrhceal discharge is placed in a 

 tube with human blood serum at 40 C., and two reductions made in the 

 usual manner (see Technique, 112) into two other blood serum tubes 

 at 40 C. In these three tubes an equal quantity of 2 per cent, peptone 

 agar, previously dissolved and cooled down to 40 C., is added, and three 

 plate cultures are prepared and placed immediately in the incubator. 



